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Divestitures, Assets Held for Sale, and Acquisitions Acquisitions (Details) $ in Thousands |  | 3 Months Ended
--- | --- | ---
Apr. 19, 2018 USD ($) a | Mar. 31, 2018 USD ($) | Mar. 31, 2017 USD ($)
Business Acquisition [Line Items] |  |  |
Payments to Acquire Oil and Gas Property and Equipment |  | $ 0 | $ 75,105
Subsequent Event [Member] | Other Martin County Acquisition 2018 [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Net Acreage Acquired | a | 760 |  |
Payments to Acquire Oil and Gas Property and Equipment | $ 24,600 |  |

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- Definition The cash outflow to purchase long lived physical asset for use in the normal oil and gas operations and to purchase mineral interests in oil and gas properties not intended for resale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
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